


Changes

by Piper_Halliwell1979



Series: Changes: Destiel ABO [1]
Category: Supernatural
Genre: ABO is caused by a virus, Alpha Castiel/Omega Dean Winchester, Alpha/Beta/Omega Dynamics, Alternate Universe, Birth, Condom Fail, Dean in Heat, Doubts about pregnancy, Fluff, Fluff and Smut, Happy Ending, Knotting, M/M, Mating, Mating Bites, Mating Bond, Mating Cycles/In Heat, Mpreg, natural childbirth, safe sex, slick
Language: English
Status: Completed
Published: 2017-06-22
Updated: 2017-06-22
Packaged: 2018-11-17 09:33:43
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 3,739
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11272770
Author URL: https://archiveofourown.org/users/Piper_Halliwell1979/pseuds/Piper_Halliwell1979
Summary: Three new strains of virus hit and Dean catches the Omega strain. His body changes and so does the nature of his relationship with Castiel.





	Changes

****

Dean had been in so much pain for the past couple months that Sam had tried to take him to the ER. The elder Winchester’s solution was to imbibe copious amounts of alcohol until he passed out. They stayed at Bobby’s and avoided any hunts.

“Sam! Bobby!” Dean cried out one morning. He stumbled down the stairs from his room, nearly falling. His eyes were bloodshot and his hair and clothes were drenched with sweat. He collapsed on the kitchen floor.

“Dean? What the hell, boy? You’re burning up. That's it. Sam! We’re dragging his sorry carcass to the hospital.” Bobby grabbed a nearby dishtowel and wet it down to cool Dean off.

Sam rushed in and dropped down to lift his brother. “Damnit. His pants are wet. I think he pissed himself.”

“Wouldn’t you if you had this kind of fever and pain? And he used to change your diapers so get to lifting. I’ll put a blanket down in my car.”

***

Dean wasn’t the only one suffering from whatever virus was going around. A couple people were strapped to gurneys and under cooling blankets. Dean just rolled his head and babbled nonsense in his delirium. He had a cold saline IV started and a doctor ordered a whole series of tests. Sam and Bobby answered the questions as best they could and were shuffled out to the waiting area.

“Winchester?” a nurse called. Sam went to her hoping for any news. She just led him to a consultation room to speak with a doctor.

“You're Dean’s brother?” Sam nodded. “I’m Dr. Capshaw from the CDC. Dean came in with the same symptoms as several others in the area. He’s one of nearly a thousand cases reported across the country,” she explained.

“So he got some sort of virus? But me and our uncle are fine. We’ve been taking care of him for a couple months. What are we supposed to do?”

“This is a very unique virus, Mr. Winchester. And this is just one strain of it. Your brother has contracted what we call the Omega Virus. Carriers are driven by a primal need to mate and reproduce. The Beta Virus has rendered many sterile. The Alpha Virus has caused a mutation in male genitalia. This kind of dynamic is usually lupine in nature.”

“Wolves? Dean has a wolf virus? So he’s  burning up because he needs to  _ breed _ ?”

“Omegas need to  _ be _ bred, Mr. Winchester. Your brother is in heat and unless he is impregnated by an alpha you just have to keep him in isolation until his heat passes. We’ll get his fever below one hundred before we release him.”

Sam scoffed. “Did Dean put you up to this? He’s a cisgender male. He can’t get pregnant.”

The doctor set down her chart and showed the scans to Sam. “That abdominal pain he’s been having? Your brother was successfully growing a womb, ovaries, fallopian tubes, and a cervix.”

Sam’s jaw dropped. “How often would he get these heats?”

“About three times a year if the human virus remains similar to lupine biology.” She went to stand. “Be watchful for your brother. Alphas can smell heat and they have little impulse control when they are in a rut. He could get hurt.”

“Does he know all this?” Sam asked quietly. He was reeling from all this information. “Is there like a test to see if you have one of the viruses? I can’t...I can’t…” he pounded his fist on the table.

“He knows. And you can submit your blood for testing but I can almost assure you that you won't attack your brother. You couldn't smell the pheromones from his heat. Go home, Mr. Winchester. Get some rest. Make him a safe place.”

Sam nodded and allowed himself to be ushered back to Bobby. “Well?”

“You won’t believe this.”

***

Bobby made a decent nest for Dean in the panic room. If it could hold a blood junkie it could definitely hold a grown man in heat. From what he and Sam read about wolves and werewolf lore they estimated Dean had about five more days of misery. They even learned that he wasn’t incontinent from fever. He was producing something called slick to attract an Alpha for mating.

Dean hated his body. He sat around in Depends to catch the waves of slick that gushed from him. His dick stayed hard and it was just as painful to leave it alone as it was to try to get relief. He drank nearly a gallon of water a day and sweat out almost as much. And the cramping. He felt like he was full of broken glass.

Sam eventually prayed to Cas. He was rarely answered like Dean was but hearing his brother cry and howl...maybe Cas could use some grace to help him or at least knock him out so he could rest.

Castiel fluttered in, startling Sam and Bobby. He sniffed the air. “Dean!” He charged for the panic room door but the two men stopped him.

“Dean’s not himself, Cas.” Sam warned.

“He’s in heat. I can smell it through the iron door. He needs a knot.”

“A what?” Bobby looked confused.

Cas rolled his eyes in his ever frustration with his human charges. “In other dimensions this is common. Omegas are receptive to the Alpha’s knot which locks them together during breeding to ensure the seed its best chance at causing pregnancy. The knot deflates and they uncouple. This repeats several times until the heat subsides or the Omega has caught.”

“Where the hell were you when we didn't know what was happening to him? Can’t you zap him out of it?” Bobby got gruff.

“Cas! Cas!” Dean pounded on the door. His eyes were even wilder than usual. “Alpha  _ please _ !” 

Sam and Bobby focused on the angel. Castiel removed his trench coat, jacket, and tie. “I  _ am _ an Alpha. At least my vessel is predisposed to be. Dean needs my assistance. You may not wish to be here for the...coupling.”

“Whoa, wait. You’re just going to go in there and screw my brother? He’s all messed up in the head, Cas! He can’t consent. No. Not letting you in there.” Sam blocked the door. He imposed his height on Castiel, hoping it would deter him without Bobby blasting him out with a banishing sigil.

“Then what would you have me do? He is in excruciating pain and I feel the biological imperative to make that pain go away, to protect him, to  _ mate.”  _ Castiel stopped pacing. “He’s my mate! I have to go to him.”

Bobby cocked his shotgun. He stepped in beside Sam. “If he’s your mate you can sniff it out after his heat passes. I know that much from werewolves. They bond before cycles so they can sync up the ruts. Now knock out the idjit and come back next week.”

Castiel wanted to challenge them but he suppressed his urges and nodded. He waved a hand and they heard the thud of Dean’s unconscious body hit the floor. Cas left in the same flutter of ethereal wings flapping.

***

Dean woke up shivering. He crawled across the floor, teeth chattering. He found the blankets Bobby had left him by the cot. He covered himself in layers until he felt his body temperature stabilize. “Sam!”

His brother appeared at the small window. He jerked open the door and went to Dean. “Hey! Is it over? You’re not sweating.”

“Shower, bacon, beer,” Dean muttered. Sam helped him stand and get up the stairs. He brought Dean fresh clothes and set them on the sink whilst he showered. Bobby worked on the breakfast.

They let him wolf down two plates of biscuits and gravy and a beer before asking him any questions. Dean spoke up first, though.

“That was worse than hell. Doc said I gotta go through that three times a year?”

“Do you remember Cas being here?” Sam ventured.

“Yeah. He smelled...he smelled like everything that ever made me feel good or happy. I wanted him...I mean...the Omega wanted him to mate and breed. How crazy is that?”

“Dean, Cas said you smelled like his mate, too. And if that's true it’ll make you even more miserable to deny it.” Bobby said in his sage wisdom. “I told him to come back and scent you when that mess was over.”

Dean pushed away from the table. “Damnit, Bobby! I don’t want this! I don’t want a mate to breed me and keep me knocked up. It’s not who I am. It's just a virus.” He stood up and stormed out to the garage where he stashed a half bottle of bourbon and a crumpled box of Marlboros with two smokes left.

He sat down in the front seat of the Chevy wagon Bobby had the engine out of. It was barely ten in the morning but he chugged his liquor anyway. He lit up a cigarette and nearly choked on the first drag. After the third he was good.

“Dean?” 

He startled and dropped his bottle. Almost burned himself with the cigarette too. “Jesus, Cas, stop sneaking up on me.” 

“Bobby told me to return in a week to discuss our mating.”

Dean sneered and pulled a long draw before tossing the butt and snuffing it when he stepped out of the car. “Not happening.”

“Dean, you can’t deny this pull we have toward one another. I know you smelled it, too. It’s called a scent bond. You know we are true mates.”

“Listen, I got a virus, okay? That doesn't change who I am and Dean Winchester is nobody’s bitch. You got that?”

Cas closed in on his personal space. “You smell like  _ home _ , Dean.”

“You do, too,” Dean replied through gritted teeth. 

“Then why fight this? I can protect you. Other Alphas will see you are mated and they will not win if they challenge me.”

“I can protect myself just fine.”

“Dean,” Castiel whispered as he nuzzled into Dean’s neck.  _ Mate, knot, claim _ went through his mind in a mantra. His teeth grazed the spot where Dean’s mating gland should be. One bite and Dean would be his.

Dean growled. He wanted to push Cas away but something inside just pulled him in closer.  He breathed in that wonderful, comforting scent. His instinct was to bare his neck for his Alpha, to be claimed. “Fuck. Just do it.” He whimpered.

He felt euphoric, then...not so different. He expected to feel...feminine, maybe? Domesticated? He felt like himself only content for once.

“Now me, Dean. Equal partnership. Claim me back.” Cas urged. He bared himself for his mate. Dean sank in his teeth and completed their bond.

“So now what?”

“Now we are mated, Dean. We protect each other, take care of each other. And I will be with you during your heats to ease your pain with our coupling.”

Dean started to argue that he didn’t want to be bred. He didn’t want to have crazy sex with his best friend. But those thoughts turned fuzzy and all he could see clearly was his mate making love to him and admiring his belly swollen with their pup.

“Ugh. Fuck! That bite did something to me.” Dean shook his head.

Cas put a hand on the back of Dean’s neck. It had the calming effect he intended. “Talk to me.” He pleaded with a softened expression.

“I just got all these images in my head. It’s like I  _ want _ you to knock me up.”

“Dean, we can use contraceptive measures during your heats and any other times we...make love. I would never force you to carry a child. Do you think being an Omega means you must defer to me? I told you we are equal.”

“You wanna...outside of heats?”

Cas took Dean’s hands in his and looked up into his eyes. “Yes. This is not a ‘marriage of convenience’ to me. I intend to honor our bond as mates.”

“What about all the shit going on upstairs?”

“Our mating bond supersedes that. I will not leave you again.”

Dean dropped his head to Cas’ shoulder. He was so confused on what he was now. Was he the  _ wife _ of an angel? Could he still hunt? Where were they supposed to live? Bobby's? And why did just the scent of Castiel make him not care about any of it because they were together?

“You’re thinking too loud again,” Cas muttered. “Home is where you are. Being Omega does not make one less masculine. And your scent makes me want to curl up in bed with you and shut the world out.”

“Damnit.” Dean felt his slick start to leak. The mention of being in bed flushed his skin and made his new anatomy react. “What are you doing to me?”

Cas grabbed Dean’s hand and brought it to the front of his trousers. “The same thing you’re doing to me.”

Dean started to ache to be filled. Not as urgently as when he was in heat but he wanted Cas inside him  _ now. _ He fumbled for the door handle to the backseat of the wagon. With a rusty creak he opened it and fell backward onto the bench seat.

Cas was on him immediately. His lips found Dean’s and they were met eagerly. Cas wasted no time stripping them with his grace. His body was hot on Dean’s and the smell of the slick was driving him crazy.

“I want to taste you, Dean. You smell so good.”

Dean turned to get on all fours, presenting himself to his Alpha on instinct. He felt his damp cheeks part and the angel’s tongue dive right into him. He mewled and whimpered, backing into Cas. His cock was already hard and heavy. He reached for it to seek some relief but he knew it wouldn't come until he was filled.

“Cas, please. Need my Alpha.”

“Patience, love. I won’t hurt you.”

Cas added a finger beside his tongue in the glistening hole. Dean just moaned and continued rocking back. He begged again to be filled. “Dean, do you have...protection?”

“Shit. Probably. My heat’s over. I can’t get pregnant, right?”

“You’re one day off of it. It’s still a risk.”

“Okay, conjure up a rubber and get inside me.”

Cas concentrated on where Dean might keep them but wound up snagging one from Sam’s wallet. He had to ask for assistance from Dean on how to use it. After getting him properly sheathed Dean guided him in and sank back down.

“Oh fuck, Cas. You feel so big. I’ve never…”

“Nor have I, love, but this feels indescribable.”

Cas let his instincts take over and rolled his hips. Dean cried out but not from pain. This was what he  _ needed _ . He finally felt the fullness his body craved. He continued to leak slick and momentarily was thankful for the built in lube. 

“Dean, this pleasure...it’s overwhelming.” Cas grabbed his hip and moved a little faster, a little harder. “I’m getting my knot, are you ready to take it?”

“Give it to me, Alpha. Need it. Need your knot.”

Cas pushed it past Dean’s rim, causing him to make shorter thrusts. Dean howled as the knot pressed his prostate and his dick felt like the cum exploded from it. Spurt after spurt hit the vinyl as he finally got the release he couldn't find during his heat. Cas nuzzled into Dean’s mating mark and started filling the condom.

He went to pull out but his knot was caught. It caused another orgasm to pulse from him. He decided it would be best to maneuver Dean into his lap until the knot was gone. Dean just sighed with contentment and practically purred at Cas’ touch.

“I like coupling with you, Dean. I would like to do this again.”

“Yeah, me too. Umm...so I never thought this would happen. Mated to an angel, riding a dick…”

“Human sexuality is not binary. It’s more fluid. It was my Father’s design to give humans pleasure as well as a means for procreation. Angels don’t have a gender if that makes our situation better for you. Although with Jimmy gone this male vessel is entirely mine.”

“So I’m not gay?”

“Must you label this? Can we just be mates?”

“The world is gonna see us as two dudes,  _ gay _ dudes. We’re gonna face some challenges. Just want you to be aware of that.”

“I would smite anyone who would attempt to harm you.”

“I’d kick some ass for you, too.”

***

“You wouldn't get so sick if you didn't eat all that greasy food, Dean. A salad every now and then wouldn't kill you.” Sam handed Dean a towel. 

“What if my next heat’s coming early? It’s only been two months.” Dean leaned back against the bathroom wall. They’d decided to stay with Bobby for awhile. Cas only flitted away for a day at most to deal with angel crap. 

“Cas will be back tonight. He can smell it on you if you are.”

“Yeah, you and Bobby lucked out with the Beta strain. Nothing messed with your plumbing.”

“And I’m sterile as an operating room. Great trade off.” Sam scrunched up his face. “Wait...you didn't start throwing up until this morning right?”

Dean glared at him. “Don’t. We used a condom, okay? We use them every time.”

“Condoms break, Dean. Or maybe Alpha’s have super sperm. I don’t know. “

“If I ever hear the words ‘super sperm’ come out of your mouth again…”

Sam put his hands up and walked away. Dean went back to heaving. When he thought it had let up he crawled back to his bed and passed out for a nap. He only realized he’d slept the day away when his mate roused him later that evening.

Cas curled up behind him and searched for his comforting scent of  _ home _ and  _ mate.  _ “Oh, Dean...I’m so sorry.” He stroked his hair.

“Sorry for what?” Dean rolled over to face him.

“Your scent is different. I didn’t mean for this to happen.”

“Talk to me. What’s going on?”

“You’ve caught, Dean. There’s a new life in you.”

Dean went to his back and put a hand over his eyes. “I was afraid of that.”

Cas pulled him close. “We’ll do whatever you decide,” his hand dropped to Dean’s stomach, “but I do want this.”

Dean started crying. “I kind of do, too. But this life isn’t for kids, Cas. What if something happens to us and our kid is left an orphan?”

“What happened to you? Bobby stepped in and became a father to you and Sam. Sam would do the same for us.”

“You really want a baby?”

“Yes. But not at the cost of you. You are my love, Dean. My life. I will defer to your wishes.”

More tears streamed down Dean’s face. “I love you so much, Cas. A big part of me wants this too, with you, for you. I’m just scared.”

Cas gently thumbed the tears away and kissed his mate. “I’m scared, too.”

Dean allowed himself a smile and placed his hand with Cas’. “So we’re doing this. We're having a baby.”

“We’re having a baby,” Cas smiled back.

***

“Calm down, son. There's been a dozen other Omega births. You’re gonna be fine.” Bobby held onto him and walked him to the van. Sam was in the driver’s seat and Cas was in the back with a blanket. He took Dean from Bobby and helped him breathe through the contraction.

“I want a fucking C-section!” Dean yelled. He clutched at his mate. “Knock me out, baby, please!”

Cas used a bit of grace to dull the pain. “I cannot interfere with the natural course of birth. I can help the pain but this child is coming at it's own time.”

“Goddamnit, you try being in labor and wondering how I’m gonna get this out of  _ this _ ,” he gestured at his crotch.

Sam got them to the hospital where a special delivery team was waiting. Dean’s pregnancy had been carefully monitored. Luckily he was one of the two single births. The others had two or three pups. Cas stayed by his side the whole time until he was handed scrubs and told to change.

“Cas! Please! Tell them I want a C-section!” Dean screamed. Another contraction hit him almost immediately after one.

“It’s too late for that, Mr. Winchester,” his doctor told him. “You’re already dilated and ready to deliver.”

“Then tell them I want my tubes tied. This ain’t happening again.” He panted and squeezed Cas’ hand.

“We’ll discuss that later, love. Now you need to concentrate on the pup, okay?”

Dean whined but he nodded. The pressure was intense and he wanted to push. He wanted it to be over. The doctor told him he could bear down on the next contraction.

It took twenty minutes before a very exhausted Dean heard his son’s first cry. Cas left his side to cut the cord and watch as their baby was tended to by the medical team. 

“Congratulations, guys. You have a perfectly healthy baby boy. Six pounds and eight ounces.” She handed Dean the swaddled baby and he just wept with joy.

“We did this, Cas. We made a baby.”

Cas kissed his sweat soaked temple then kissed their newborn on his forehead. “I think we should name him Hunter.”

“Hunter. I like it. Family name. Hunter Robert Samuel Winchester.”

“It’s perfect, Dean. Just like he is.”

They scented their tiny bundle, bonding as a family before letting Bobby and Sam into the recovery room. Sam beamed at hearing his nephew was his namesake. Bobby tried to hide his emotions when Dean referred to him as Grandpa. 

“You did good, son. Real good. Looks like I’ll have to dig out your old mitt so we can play catch.” Bobby bounced the little one. “You two idjits got yourself a real pistol here.” He handed the baby over to Cas. 

The angel was full of emotions he never knew he could experience. His love for his mate was only matched by the love for his tiny pup. He cried for the first time, looking into those dark blue eyes. He cried for the second time when he signed Castiel Winchester on the birth certificate.

**Author's Note:**

> I'm fairly new to writing ABO dynamics so I hope you enjoyed this AU piece


End file.
